Running is one of the most popular forms of physical activity and is associated with significant health benefits and positive effects on mortality. However, the joint impact caused by running has led to some fears that it may increase the risk of osteoarthritis through degradation of joint cartilage. Therefore, this systematic review with meta-analysis aimed to evaluate the effect of running on knee joint cartilage.
A database search yielded 15 eligible articles involving 529 participants (2 randomised controlled trials and 13 cohort studies). Study quality was assessed using the GRADE approach and ranged from moderate to low. The chosen outcomes were cartilage volume and thickness, the amount of cartilage oligomeric matrix protein (COMP), and the knee cartilage T2 relaxation time (a measure of water content).
A decrease in knee cartilage thickness and T2 relaxation time after running was reported in the included studies. There was also a short-term decrease in COMP content up to 30 minutes which was no longer significant 1 and 2 hours after running. Thus, running showed no persistent negative effects on knee cartilage volume. Further research of higher methodological quality remains needed.
> From: Dong et al., Phys Ther Sport 47 (2021) 147-155 (Epub ahead of print). All rights reserved to Elsevier B.V.. Click here for the online summary.
Expert opinion
Although the quality of studies is not ideal, the results from this review are in line with those of other reviews which point to beneficial effects of axial load on different joint tissues.
This review should therefore be another encouragement not to advise patients to take up swimming to avoid “damaging their knees”. Naturally, there is nothing wrong with swimming itself (especially if patients enjoy it), but the message to avoid joint loading may not only have an effect in tissue quality (as the review shows) but also promote fear of movement and decrease participation in the long term, which would cause further deconditioning and pain.
The main take-home message, then, should be to empower patients to keep up loading activities they enjoy and not promote avoidance (unless, of course, there are other contraindications to physical activity).
